refactor(frontend): P1-P2 架构统一 — utils/hooks/api 模块化

P1:
- utils/storage.ts、theme.ts、validate.ts + index 统一出口
- request/store/useTheme 接入 storage；清零 confirm/alert
- PipelineManager、TerminalAuditTab 拆分子模块（<700行红线）

P2:
- api/monitor、api/deploy 子目录化
- hooks/api 扩展：servers/pipelines/alerts/audit/sessionCommands
- PipelineManager、AuditOperationsTab 接入 TanStack Query

frontend/src/api/monitor/grafana.ts

@@ -0,0 +1,10 @@
+// Grafana 仪表盘 API（暂无后端，返回空结果优雅降级） // Logan.Li
+
+export const dashboardApi = {
+  getDashboards: async (): Promise<{ data: any[]; total: number }> => ({ data: [], total: 0 }),
+  getDatasources: async (): Promise<{ data: any[]; total: number }> => ({ data: [], total: 0 }),
+  createDashboard: async ( _data: any) => ({ success: false }),
+  updateDashboard: async (_id: number | string, _data: any) => ({ success: false }),
+  deleteDashboard: async (_id: number | string) => ({ success: false }),
+  createDatasource: async ( _data: any) => ({ success: false }),
+};